The present invention relates to the field of guide mechanisms and methods of transversely positioning a tape media across the face of a transducer.
One method of increasing the density of data stored in a tape media is to reduce the width of data tracks written therein. The narrow data tracks in turn require a tighter tolerance be maintained for the transverse positioning of the tape media with respect to a transducer. A common method for transverse positioning the tape media is to bias either its top edge or the bottom edge against a stationary or rotating reference edge guide. As long as the edge of the tape media does not buckle at the reference edge guide, high tracking accuracies can be maintained between the data tracks on the tape media and the transducer.
Positioning of the tape media in the transverse direction usually requires some transverse bending of the tape media. This bending can introduce stresses and strains in the tape media that reduce its useful life span. Contact between the tape media edges and the referenced guide surfaces causes wear and tear on the tape media edges over prolonged periods. Edge wear and damage can result in increased tracking errors and result in the generation of particulates that can interfere with the read-write process between the tape media and the transducer.
Close mechanical tolerances must be maintained between a tape media storage spool and the tape guides to minimize the transverse bending of the tape media and the force with which the tape media edges contact the storage spool. Tracking errors are especially noticeable where the tape media leaving the storage spool is misaligned with the edge guides that transversely position the media before the transducer. Misalignments can be due to conditions such as stagger wrap and pre-stress in the tape media as it is wrapped around the storage spool. Mechanical misalignment and design tolerance stacking between the storage spool, a cartridge housing surrounding the storage spool, and cartridge mounting hardware holding the cartridge can also play a significant role in creating tracking errors. Other factors include manufacturing defects in the storage spool and cartridge housings, manual handling dynamics of the storage spool and cartridge, robotic handling dynamics of the storage spool and cartridge, shelf-life problems, and environmentally induced creep, shrink and stretch due to temperature, humidity and tension/handling stresses.
The present invention is a guide mechanism and a method for positioning a tape media in a transverse direction with respect to a transducer as the tape media is moved from a first spool to a second spool. A first surface guide is disposed between the first spool and the transducer. This first surface guide engages at least one of the two surfaces of the tape media to orient the tape media non-planer with respect to the transverse direction. This orientation reduces the tape media stiffness in the transverse direction, making the tape media easier to bend in the transverse direction. A second surface guide is disposed between the transducer and the first surface guide. The second surface guide engages at least one of the two surfaces of tape media to orient the surfaces approximately parallel to the transverse direction. In this orientation, the transverse stiffness of the tape media is at its maximum, and the media-side surface of the tape media is now parallel to the face of the transducer. A first edge guide is disposed adjacent to the transducer. The first edge guide engages at least one of the two edges of the tape media to precisely position the tape media in the transverse direction. The first edge guide may be mounted on, or mounted independent of the second surface guide.
A mirrored set of surface guides and an edge guide may be disposed between the transducer and the second spool to provide highly accurate transverse positioning when the tape media moves from the second spool across the face of the transducer and back to the first spool.
In the preferred embodiment, the first surface guide orients the tape media surfaces into a plane normal to the transverse direction. This requires the first spool""s axis of rotation also to rest in a plane normal to the transverse direction. Here, the tape media leaves the first spool and then undergoes a 90xc2x0 twist between the first surface guide and the second surface guide. The first edge guide provides final transverse positioning of the tape media just before it engages the transducer. Finally, the tape media is wound around the second spool.
A second twist can be introduced in the tape path to allow the first spool, the second spool, and the transducer to remain in a common plane. The second twist is caused by an additional surface guide disposed between the first surface guide and the first spool. This additional surface guide engages at least one of the two tape media surfaces to orient the tape media surfaces approximately parallel to the axis of rotation of the first spool which itself is parallel to the transverse direction.
Accordingly, it is an object of the present invention to provide a guide mechanism for transverse positioning a tape media with respect to a transducer that utilizes the lower lateral stiffness of the tape media, as compared with the transverse stiffness, to allow the tape media to be easily positioned in the transverse direction.
Another object of the present invention is to provide a method of positioning a tape media in a transverse direction with respect to a transducer that utilizes the lower lateral stiffness of the tape media, as compared with the transverse stiffness, to allow the tape media to be easily positioned in the transverse direction.
These and other objects, features, and advantages will be readily apparent upon consideration of the following detailed description in conjunction with the accompanying drawings.